The proposed study focuses on understanding and developing new methods to diagnose low back pain[unreadable] problems resulting from both segmental instability and degenerative changes in intervertebral discs and/or[unreadable] facets. In the ongoing study, we found that a relationship exists between the severity of intervertebral disc[unreadable] degeneration and increases in torsional and flexion-extension movements. Significant differences were[unreadable] found in facet degeneration and disc degeneration between the asymptomatic and the symptomatic[unreadable] subjects. However, the mechanistic relationship between disc degeneration and the facet joint remains to[unreadable] be clarified. In Project 1 of the renewal Program Project Grant, we will define kinematic hypermobility in[unreadable] torsion and flexion-extension in vivo and correlate those measurements with low back pain symptoms. We[unreadable] will identify factors of prognostic importance to the progression of disc and facet joint degeneration and[unreadable] symptoms. We propose a five-year study of the in vivo relationship of degenerative changes with segmental[unreadable] instability of the lumbar spine. In this proposed study, we will re-evaluate, over a five-year interval, 25[unreadable] asymptomatic normal subjects and 25 age- and sex-matched symptomatic subjects, who were investigated[unreadable] in the current grant cycle. Hypotheses that we will test in this study are (1) that greater segmental mobility[unreadable] and/or specific kinematic patterns contribute to accelerated intervertebral disc and facet degeneration over[unreadable] time, and (2) that load transmission through the facet joints depends on the loading direction and[unreadable] intervertebral disc degeneration and height, and motion segment level and facet orientation. The specific[unreadable] aims are (1) to measure changes in rotational and flexion/extension segmental movement associated with[unreadable] disc and facet degeneration over five years within each subject (a longitudinal in vivo study comparing[unreadable] normal subjects and mechanical low back pain subjects), and (2) to investigate, using cadaveric lumbar[unreadable] spines, relationships among disc degeneration and height, segmental movement, disc pressure and facet[unreadable] joint pressure, and to analyze correlations between altered kinematics and load transmission (an[unreadable] experimental in vitro study). The outcome from the proposed study is expected to be equally effective for[unreadable] diagnosis of cervical spinal instability and evaluating many of new motion preservation treatment alternatives[unreadable] in use or under development.